The present embodiments relate to wireless communication systems and, more particularly, to Coordinated Multi-Point (CoMP) transmission in which a single mobile unit communicates with plural base stations.
In legacy wireless cellular systems such as Long Term Evolution (LTE) Rel. 8 to 10, a wireless network includes multiple base stations. Each base station may be configured as a single cell with its own cell ID. Mobile terminals or user equipment (UE) always connect to and exchange uplink (UL) data and downlink (DL) data with a connected cell in single-cell transmission/reception.
CoMP stands for Coordinated Multi-Point Transmission. In CoMP multiple transmission points (TP) such as a cell, macro eNB, pico eNB, femto eNB, remote radio heads, distributed antennas, other wireless transmission entity or a combination of these coordinate with each other to jointly optimize downlink beam forming signals. These include beam forming vectors, transmission power and/or scheduling decisions. In contrast to traditional wireless networks without cell coordination where signals from other transmission points impose as co-channel interference, coordination within multiple TPs allows the signals to be cooperatively designed to reduce co-channel interference, boost received signal to noise ratio (SNR) and improve cell-average throughput and cell-edge coverage.
It is expected that CoMP in Rel. 11 is based on non-codebook-based beam forming with UE reference signals (UE-RS). UE-RS is equivalently referred to as demodulation reference signals (DMRS). This patent application proposes a transparent design of CoMP.